Sequential C−H Borylation and N-Demethylation of 1,1′-Biphenylamines: Alternative Route to Polycyclic BN-Heteroarenes

Abstract

© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Described herein is an unprecedented access to BN-polyaromatic compounds from 1,1′-biphenylamines by sequential borane-mediated C(sp 2 )−H borylation and intramolecular N-demethylation. The conveniently in situ generated Piers’ borane from a borinic acid reacts with a series of N,N-dimethyl-1,1′-biphenyl-2-amines in the presence of PhSiH 3 to afford six-membered amine-borane adducts bearing a C(sp 2 )−B bond at the C2′-position. These species undergo an intramolecular N-demethylation with a B(C 6 F 5 ) 3 catalyst to provide BN-isosteres of polyaromatics. According to computational studies, a stepwise ionic pathway is suggested. Photophysical characters of the resultant BN-heteroarenes shown them to be distinctive from those of all-carbon analogues ⓒ 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim